The long term objective of the present study is to understand abnormal growth of the human prostate, namely, benign prostatic hyperplasia (BPH) and prostate carcinoma. The present study deals with the effect of non-androgenic endogenous factors, specifically prolactin and autonomic neurotransmitters, on the rat prostate. The present study is proposed with the content that factors other than the male sex steroid hormone are involved in prostatic growth. Results of our preliminary studies seem to support the above concept. Furthermore the effect of prolactin seems to be preferentially on the lateral lobe of the rat prostate while the effect of autonomic neurotransmitters seems to be on the ventral lobe. These observations may have important implications in human prostatic growth. The present study is proposed to use the rat prostate as an experimental model to study the biology of the effect of prolactin and autonomic neurotransmitters. They will be considered separately. The role of autonomic innervation in prostatic growth is a relatively new subject. This requires careful preliminary studies to characterize the organization of innervation of the prostate first. Next, the study of the effect of innervation on prostatic growth can also be studied by the technique of two-dimensional electrophoresis and autoradiography of the prostrate following in vitro incubation with radiolabeled amino acid. Finally, the acute effect of autonomic nervous system stimulation on the rat prostate secretion will be studied by the technique of two- dimensional electrophoresis in the presence or absence of various pharmacological blockers to determine the specificity of the response of the postrate. There is ample experimental evidence to indicate that the rat prostate, especially the lateral lobe, is a target tissue for prolactin. However, the exact mode of action of prolactin in prostatic growth and function remains unclear. It is particularly unclear regarding the type of biological events that take place following prolactin binding to the cellular membrane of the prostate. Our hypothesis is that prolactin could be acting in the rat prostate by an activation of genetic expression mechanism and/or by modification of post-translational products. The use of the technique of two-dimensional gel electrophoresis has made it possible for us to study synthesis of individual proteins in the prostate following prolactin stimulation.